Problem: $\dfrac{2}{5} - \dfrac{1}{5} = {?}$
Answer: $ = {\dfrac{2 \times 1}{5 \times 1}} - {\dfrac{1 \times 1}{5 \times 1}} $ $ = {\dfrac{2}{5}} - {\dfrac{1}{5}} $ $ = \dfrac{{2} - {1}}{5} $ $ = \dfrac{1}{5}$